QtKeychain is a Qt API to store passwords and other secret data
securely. How the data is stored on Linux:

If running, GNOME Keyring is used, otherwise qtkeychain tries to
use KWallet (via D-Bus), if available. In unsupported environments
QtKeychain will report an error. It will not store any data
unencrypted unless explicitly requested
(setInsecureFallback( true )).

If this is built against the optional dependency qt5 it will use
that instead of qt-4.x.